Re: [RFC 4/6] tests: tpm-emu: Remove assert on TPM2_ST_NO_SESSIONS

[Auger Eric]

Hi Stefan,

On 6/2/20 6:17 PM, Stefan Berger wrote:
> On 6/2/20 12:13 PM, Auger Eric wrote:
>> Hi Stefan,
>>
>> On 6/2/20 3:39 PM, Stefan Berger wrote:
>>> On 6/1/20 6:21 AM, Eric Auger wrote:
>>>> While writing tests for checking the content of TPM2 and DSDT
>>>> along with TPM-TIS instantiation I attempted to reuse the
>>>> framework used for TPM-TIS tests. However While dumping the
>>>> ACPI tables I get an assert on TPM2_ST_NO_SESSIONS. My assumption
>>>> is maybe the other tests did not execute long enough to encounter
>>>> this. So I tentatively propose to remove the assert as it
>>>> does not seem to break other tests and enable the new ones.
>>>>
>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>>> ---
>>>>    tests/qtest/tpm-emu.c | 1 -
>>>>    1 file changed, 1 deletion(-)
>>>>
>>>> diff --git a/tests/qtest/tpm-emu.c b/tests/qtest/tpm-emu.c
>>>> index c43ac4aef8..298d0eec74 100644
>>>> --- a/tests/qtest/tpm-emu.c
>>>> +++ b/tests/qtest/tpm-emu.c
>>>> @@ -49,7 +49,6 @@ static void *tpm_emu_tpm_thread(void *data)
>>>>            s->tpm_msg->tag = be16_to_cpu(s->tpm_msg->tag);
>>>>            s->tpm_msg->len = be32_to_cpu(s->tpm_msg->len);
>>>>            g_assert_cmpint(s->tpm_msg->len, >=, minhlen);
>>>> -        g_assert_cmpint(s->tpm_msg->tag, ==, TPM2_ST_NO_SESSIONS);
>>> You should not have to remove this. The tests are skipped if swtpm does
>>> not support TPM 2 via --tpm2 option. This would be a very old swtpm
>>> version, though. So, all tests are run with --tpm2 option and any
>>> response received from the TPM would be a TPM 2 response that should
>>> have TPM2_ST_NO_SESSIONS as the tag. I'd be curious what other value you
>>> are seeing there.
>> If I revert this patch I am getting TPM2_ST_SESSIONS on my end.
> 
> Is firmware/BIOS active? There's no TPM2_ST_SESSIONS coming out of QEMU.

So it looks SeaBIOS is in use (bios-256k.bin loaded).

I can see MMIO accesses to the TPM and the following commands are
observable:
tpm_emu_tpm_thread code=0x181 tag=0x8001 len=0xa
tpm_emu_tpm_thread code=0x144 tag=0x8001 len=0xc
tpm_emu_tpm_thread code=0x121 tag=0x8002 len=0x20
This last one causes the assert (TPM2_CC_HierarchyControl)

I checked in Seabios and effectively tpm20_hierarchycontrol() tags the
TPM2_CC_HierarchyControl command with TPM2_ST_SESSIONS

Due to our emulation, maybe tpm_set_failure() gets called, inducing
tpm20_hierarchycontrol() call.

That being said, what do you recommend? Remove the assert, improve the
emulation, other?

Thank you in advance

Best Regards

Eric

> 
>    Stefan
> 
> 
>